US3548154A

US3548154A - Electric heating oven

Info

Publication number: US3548154A
Application number: US808077A
Authority: US
Inventors: Olof Fingal Christiansson
Original assignee: ANKARSRUMS BRUK AB
Current assignee: ANKARSRUMS BRUK AB
Priority date: 1968-12-03
Filing date: 1969-03-18
Publication date: 1970-12-15
Anticipated expiration: 1987-12-15
Also published as: SE331525B

Description

United States Patent Olot' Fingal Christiansson [72] inventor 1,982,386 11/1934 Heinbuch... 219/403 Allklmmvswedell 2,024,386 12/1935 Phelps 2l9/403X [21] Appl- 803,077 2,668,222 2/l954 McCormick 2l9/403X Filed 1969 2,994,760 8/1961 Pecoraro etal.... 2l9/409X 1 Patented Des-15,1970 3,270,660 9/1966 Filipak 99/340 g Aktkbohset Ankflrsrumsllruk 3,358,120 12/1967 Schibley 219/403x Ankarsrum, Sweden P E v I d Y M k acowmonorswden AZmary xggnmergA (i= Znmdyr ayews y 32 Priority Dec. 3, 1968 [33] Sweden [31 No. 16492/68 [541 ELECTRIC "EATING OVEN ABSTRACT: An electric oven into which heating elements 22 Claims, 11 Drawing Figs.

- are lnsertable at different levels m a vanety of operative pos|- US. Clti E h h i element can be inserted into and removed from any one of the operative positions to provide widely diflll. Cl. fe ent heating patterns in the oven The heating elements in their operative positions form part of a heating circuit con- 1, 3951437, 523, 5 339 nected by a relay to a source of electrical energy. The relay normally is open and disconnects the heating elements from [56] References cited the source of electrical energy. When a control circuit is UNITED TA PATENTS completed the relay becomes operable to connect the heating 1,897,879 2/l933 Antrim 219/403 elements to the source of electrical energy.

1;- 26 g /2 l u In 1 a I n il 63m 5/ M 63 e I 63 M w '0 r: T: r

t, 25 28 f4- "HI J,

f t. "'11., '9 w SHEET 2 OF 5 PATENTEU Dim Sum 3,548,154

' sum u or 5 ELECTRIC HEATING OVEN BACKGROUND OF THE INVENTION 1. Field of the Invention Electric ovens often are equipped with a plurality of heating elements which can be shifted between several operating positions at different levels to provide a variety of heating patterns for treating food. v

2. Description of the Prior Art It has been the practice heretofore to provide electric ovens having a plurality of heating elements therein which can be moved to a number of operating positions 'atdifferent levels, as disclosed in British Pat. No. 1,1 19,350, for example.

Heating elements also have been provided in which the plane of a heat emitting surface of an' element is offset vertically with respect to the region at which the heating element is connected to an electrical outlet. Such an arrangement is disclosed in British Pat. No. 1,123,747, for example, which enables a heating element to be removed from a first operating position, reversed or turned over, and then inserted within the oven to a second operating position with the'heat emitting surface shifted vertically'with respect to' its first operating position. These prior art disclosures make it possible to treat a variety of foods of different size and shape and requiring different vertical heights in an oven to accommodate the foods to be treated.

In prior art disclosures like those referred to above the circuits of the electrical outlets to which the heating elements are connected are provided with individual manually operable switches. With this arrangement each switch in a circuit having a heating element connected therein'must be individually closed to render the heating element operable. Alternatively, each switch in a circuit in which no heating element is connected should be opened. This is objectionable because it places a burden on a user to close and open certain switches for a particular food treatment in order to exercise complete control of an oven during its operation.

A user sometimes may close a particular switch and provide electrical energy for a circuit having an electrical outlet in which no heating element is connected which is undesirable. When a user fails to close only those switches required to provide electrical energy for particular heating elements, the heating pattern desired will not be realized and food in the oven will not be properly treated. When batches of food requiring different treatment are successively treated in an oven and it is necessary from time to time to shift the positions of the heating elements and'use more or fewer heating elements and use certain electrical outlets for the first time and discontinue using other electrical outlets, it is a burden for a user to become involved in the operation of an oven and complete certain electrical circuits and open other electrical circuits.

SUMMARY OF THE INVENTION It is an object of the invention to provide for an electric oven having one or more heating elements an improvement for controlling such heating element or elements whereby, when the heating element or elements are inserted into the oven at different levels in a variety of operative positions, it is not necessary to close a manually operable switch in each circuit in which a heating element is used and to open a manually operable switch in each circuit in which a heating element is not used.

Another object is to provide for anelectric oven of this type, having a plurality of connecting members which are arranged vertically with respect to one another and function to maintain the heating element or elements in their operative positions, an improvement for controlling such element or elements whereby, irrespective of their arrangement in the oven and with which connecting members they are associated in their operative positions, the heating elementor elements will be connected to a source of electrical energy, without the need for manipulating individual switches for each heating element, only after the heating element or elements are in their operative positions at particular connecting members and movable structural members, in place of heating elements, are in operative positions at the remaining connecting member or members in a manner like the heating element or elements.

A further object is to provide for an electric oven of this type, in which the heating element or elements in their operative positions at the connecting members form a part of a heating circuit connected by a relay or switch means to a source of electrical energy, an improvement for closing such relay to render the heating element or elements operable to effect heating with the aid of a control circuit which is completed only after a heating element or elements or a structural member or members are in their operative positions at all of the connecting members. j g

A still further object is to provide for an electric oven of this type an improvement for controlling the heating element or elements by a control circuit having aplurality of switches connected in series, each of the switches having two cooperating contacts at each of the connecting members and contactors for closing the switch contacts, each heating element and each structural member having a contactor thereon whereby, when the switch contacts on each connecting member are closed by a contactor carried by a heating element or structural member, the control circuit will be completed and automatically cause the relay in the heating circuit to connect the heating element or elements to, the source of electrical energy.

Further objects and advantages of the invention will become apparent as the following description proceeds, and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a front perspective view of the interior of an electric oven embodying the invention, the-door being partly broken away and open;

FIG. 2 is a fragmentary front perspective view, partly broken away, of an electrical connecting member and heating element shown in FIG. 1 to illustrate details more clearly;

FIG. 3 is a fragmentary rear perspective view of the electrical connecting member and heating element illustrated in FIG. 2;'

FIG. 4 is a front perspective view of an electrical structural member shown in FIG. 1 to illustrate details more clearly;

FIG. 5 is a rear perspective view of the electrical structural member shown in FIG. 4;

FIG. 6 is a front perspective view of anotherelectrical structural member and U-shaped positioning frame therefor which are shown in FIG. I to illustrate details more clearly;

FIG. 7 is a rear perspective view of the electrical structural member and U-shaped positioning frame shown in FIG. 6;

FIG. 8 is a horizontal sectional view taken on line 8-8 of FIG. 3;

FIG. 9 is a horizontal sectional view taken on line 9-9 of FIG. 7;

FIG. 10 is an elevational view of the terminal board at the rear of the electric oven shown in FIG. 1 illustrating horizontal electrical connecting members and vertical conductors therebetween of the electric circuit for the electric oven; and

FIG. 11 diagrammatically illustrates the complete electric circuit including the terminal board connections thereof shown in FIG. 10, for the electric oven shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, an electric oven 10 embodying the invention is shown which comprises a cabinet 1 1 having an inner shell 12 arranged within an outer shell 14 and insulated therefrom with a suitable insulating material in a manner well known in the art. The inner shell 12 defines a thermally insulated interior or space 15 having lateral sidewalls l6 and 17,

top 18, bottom 19 and rear wall 20. Access to the thermally insulated space of the cabinet 11 is afforded at the front opening adapted to be closed by an insulated door 21 hinged at 22 at the front wall 23 of the cabinet. The inner wall of the door 21 is provided with a suitable ridge 24 which is adapted to bear against the inner portion 25 of the front wall 23 when the door is moved to its closed position.

Heating elements 26 of the configuration shown in FIG. 3 are positioned adjacent to the top 18 and bottom 19 of the space 15. The heating elements 26, which are of conventional type having outer insulating sheaths 27, are carried in apertured frames 28 arranged to slide in guideways or tracks formed by U-shaped channel members 29 which are fixed to vertical frames 30 mounted on the

lateral sidewalls

16 and 17 and have their open ends facing one another.

As seen in FIGS. 3 and 8, the ends of each heating element 26 terminate in a pair of pins or plugs 31 retained in a body 32 of insulating material. The insulating body is held against the bottom of an open cup-shaped vessel 33 defining a hood or shroud which is carried by members 34 on the frame 28. The plugs or pins 31 project from the insulating body 32 with their outer free ends at the vicinity of the open end of the hood 33.

A plurality of electrical connecting members or fittings 35 are disposed at the rear wall 20 of the space 15. The connecting members 35 are vertically arranged with respect to one another and are disposed in 'a single vertical row extending from the top 18 to the bottom 19 of the space 15. The con necting members comprise blocks 36 of insulating material having spaced socket outlets 37 accessible within the space 15 and pins 38 which are connected to the socket outlets 37 and project rearward and are accessible on a terminal board 39 located outside the cabinet at the rear thereof, as best shown in FIG. 10.

The insulating blocks 36 are carried by mounting plates 40 from which hollow sleevelike members 41 project forward in the space 15. The plates 40 and members 41 form open cupshaped vessels defining hoods 42 which receive the hoods 33 of the heating elements 26. When the socket outlets 37 receive the plugs or pins 31 of the heating elements 26, the

.-

hoods

33 and 42 are in telescopic relation and each heating element 26 is in an operative position and connected in a heating circuit for the oven 10. 1

As shown in FIG. 10 and diagrammatically illustrated in FIG. 11, the heating circuit includes a bus bar 43a which connects one group of pins 38 of the top three connecting members 35 and a bus bar 44a which connects the other group of pins 38 of the top three connecting members 35. In a similar manner, a bus bar 43b connects one group of pins 38 of the middle three connecting members 35 and a bus bar 44b connects the other group of pins 38 of the middle three connecting members 35. In a similar manner, a bus bar 430 connects one group of pins 38 of the bottom three connecting members 35 and a bus bar 440 connects the other group of pins 38 of the bottom three connecting members 35.

The bus bars 43a, 43b and 430 are respectively connected by conductors 45a, 45b and 450 to a conductor 46 which is connected to one terminal 47 of a source of electrical energy.

. The bus bars 44a, 44b and Mr: are respectively connected by

conductors

48a, 48b and 480 to a conductor 49 which is connected to the other terminal 50 of the source of electrical energy.

A switch 51 and an indicating lamp 52 are connected in the conductor 46 and a relay 53 is connected in the

conductors

48a, 48b and 48c. The relay 53 includes a coil 54, which is connected in a control circuit that will be described presently, and has three pairs of

contacts

55a, 55b and 550 respectively connected in

conductors

48a, 48b and 480. The relay 53 normally is biased to its open position in any suitable manner, as

47,50 and function to treat food in the space 15. It will also be understood that under these assumed conditions, heating'elements 26 in operative positions at the other connecting members 35 also will be energized and function to treat food in the space 15.

In accordance with this invention, in order to avoid the requirement for closing or opening a manually operable switch for each individual heating element 26 to develop a particular heating pattern in the oven 10, a control circuit is provided for the relay 53 which includes a plurality of switches each having two cooperating contacts and a movable contactor for closing them. The cooperating contacts 57 of each switch are located at each electrical connecting member 35. Hence, the cooperating contacts of each switch are located at every level at which a heating element 26 can be inserted into an operative position" in the oven 10.

Each heating element 26 carries a switch contactor 58 which is insulated therefrom. As shown in FIG. 8, the contactor 58 associated with each heating element 26 includes a pair of plugs or pins 580 retained in the insulating block 32 and a conductor 58b extending through a passageway in the insulating block and connected at its ends to. the rear parts of the plugs or pins 58a by threaded nuts 58c.

When the heating elements 26 are moved rearward in the oven to their operative positions at the top and bottom of the space 15, the heating elements are connected in the heating circuit in the manner explained above. At the same time the contactors 58, which include the plugs or pins 58a and conductors 58b therebetween, bridge and close the cooperating contacts 57 provided at the top and bottom connecting members 22.

As best seen in FIGS. 2 and 3, the switch contacts 57 at each connecting member 35 comprise socket outlets retained in the insulating member 36 and accessible within the space 15. The socket outlets 57 are connected to plugs or pins 59 which extend rearward from the insulating members 36 and are accessible on the terminal panel 39 at the rear of the oven 10. It will now .be understood that the socket outlets 37, which receive the pins 31 of the heating elements 26, function as one pair of contacts disposed at opposite ends of each connecting member 35; and that the socket outlets 57 function as another pair of contacts disposed between the contacts 37.

When a heating element 26 is not employed at any particular connecting member 35 in the oven, a movable structural member, having a contactor thereon, is employed in its place, each structural member being insertable into an operative position" in the oven space 15 in a manner like that of a heating element 26. Such a structural member 60 is shown in FIGS. 1, 6, 7 and 9. The structural member 60 includes a contactor 158 which is like the contactor 58 seen in FIG. 8 and described above. The contactor 158 comprises a pair of plugs or pins 158a retained in an insulating body 132 and a conductor 158k extending through a passageway in the insulating body and connected at its ends to the rear parts of the plugs or pins 158a by threaded nuts 1580. The insulating body 132 is fixed to the bottom of an open cup-shaped vessel 133 defining a hood like the hood 33 in FIG. 8.

The structural member 60 is fixed to the closed end 61a of a U-shaped frame 61 having parallel sides 61b movable in one of the guideways or tracks formed by opposing channel members 29. The forward ends of the sides 61b are provided with handles 62 which enables the structural member 60 to be moved into and from its operative position even when the oven is at an elevated temperature.

When the frame 61 is pushed rearward in the oven space 15 by the handles 62, the hood 133 of the structural member 60 will move over the hood 42 of a connecting member 35 and the outlet sockets 57 will receive the plugs or pins 158a, whereby the outlet sockets or switch contacts 57 will be bridged and closed by the parts 158a and 15812 which, as explained above, define the switch contactor.

FIGS. 4 and 5 illustrate another form of structural member 160 which is identical to the structural member 60 shown in FIG. 9 and just described. The structural member 160, instead of being fixed to a frame like the frame 61 in FIGS. 6, 7 and 9, is provided with a mounting plate 63 which serves as a hand grip to facilitate the insertion of the member 160 into and from an operative position. In FIG. 1 the mounting plate 63 of a structural member 160 is seen in its operative position beneath the hood 33 associated with the heating element 26 which is in an operative position at the top connecting member 35.

The switches, which include the switchcontacts 57 on the connecting members 35 and either the

contactors

58 or 158 for closing the contacts, are'connected in series in a control circuit diagrammatically shown in FIG. 11. FIG. 11 diagrammatically illustrates the pins 59 which project rearward through the insulating blocks 36 and are connected to the contacts 57 of the connecting members which are in the form of socket outlets accessible in the space 15, as explained above.

One of the pins 59 of each connecting member 35, except the bottom connecting member, is connected. by a conductor 64 to a pin 59 of the connecting member 35 beneath it. The control circuit further includes conductors 65and 66 which are connected to the'terminals 67 and 68, respectively, of a source of electrical energy. The conductor 65 is connected to one of the pins 59 of the bottomconnecting member 35, and the conductor 66 .is connected to one of the pins 59 in the top connecting member 35. In the conductor 66, in which the coil 54 of relay 53 isconnected, are also connected a main switch 69 and an indicating lamp 70.

In FIG. 11 it will be seen that heating elements 26 are diagrammatically shown in operative positions at the top and bottom connecting members 35. This means that the contacitors 58.associated with the heating elements 26 also are in operative positions at the top and bottom, connecting mem bers' 35 and bridge and connect the contacts 57, that is, the plugs or pins 58 are in the socket outlets serving as the contacts 57. In FIG. 11 the bridging of the contacts 57 of the top and bottom connecting members is diagrammatically represented by showing the contactors 58 connected to the pins 59 on the terminal board 39 whose forward ends, as explained above, are connected to the socket outlets or contacts 57.

Let us assume that the contacts 57 of each connecting member 35 between the top and bottom connecting members are bridged by contactors 158 forming parts of

structural members

60 or 160 respectively seen in FIGS. 9 and 5. Under these assumed conditions, the bridging of the contacts 57 of the intermediate connecting members 35 is diagrammatically represented by showing the contactors-l58 connected to the pins 59 on the terminal board 39 whose forward ends are connected to the socket outlets or contacts 57.

In view of the foregoing, it will now be seen that the

switch contactors

58 and 158 in FIG. 11 are in their closed positions, and, with the main switch 69 closed, the control circuit will be completed across the source of electrical energy 67, 68 and the coil 54 of the relay 53 will be energized to close the

contacts

55a, 55b and 550. When this occurs the heating elements 26, which are in operative positions at the top and bottom connecting members 35, will be connected to the source of

electrical energy

47, 50 and function to treat food in the space 15.

Each of the connecting members 35 includes a contact 71 in the form of a socket outlet which is carried by an insulating block 36 and connected to a pin 72 projecting from the terminal board 39 at the rear of the oven 10. As seen in FIGS. and 11 the pins 72 of all of the connecting members 35 are connected to a common bus bar 73, and the pin 72 of the bottom connecting member 35 is connected to a conductor 74 which is grounded at 75.

When a heating element 26 is in its .operative position at v position on a connecting member 35 the hood 33 associated any one of the connecting members 35, the contact 71 on the connecting member receives a pin or plug 76 which is carried by the insulating body32 at a regionthereof between the pins 58a of the contactor 58. The rear end of each pin 76 extends therewith moves over the hood 42 of the connecting member. It also will be seen that the pin 76 is longer than the

pins

31 and 58a and will engage the socket outlet or contact 72 before the

pins

31 and 58a will respectively engage the socket outlets or

contacts

37 and 57. Accordingly, when a heating element 26 is being moved to its operative position, the

hoods

33 and 42 will immediately be in telescopic relation and physically shield the current-carrying parts of the heating circuit and control circuit from a user. When this occurs the parts of the heating element 26 handled by a user will immediately be grounded due to the fact that the pin 76'is longer than the

pins

31 and 58a. This means that the sheath 27 of the heating element 26 and the frame 28 in which they are carried also will be at ground potential when the heating element is in an operative position" The structural members 60 and are also provided with pins similar to the pin 76 associated with each heating element 26. The structural member 60 shown in FIG. 9 includes a pin 176 similar to the pin 76 in FIG. 8. The pin 176 is longer than the pins 158a and its rear end, which extends through the bottom of the hood 133, is threaded to receive a tightening nut 177. The pin 176 and hood 133 in FIG. 9 function in the same manner as the pin 76 and hood 33 in-FIG. 8 to shield a user from the current-carrying parts of the heating and control circuits. Also, the U-shaped frame 61 will always be grounded before any circuit is completed due to the fact that the pin 176 is longer than the pins 158a. In a similar mariner a pin like the pin 176 in FIG. 9 and forming a part of the structural member 160 in FIGS. 4 and 5 will function to ground the mounting plate 63 before any circuit is completed when such structural member is positioned on a connecting member 35.

In view of the foregoing, it will now be understood that one or more heating elements 26 may be employed in the oven 10 at different levels therein, and, regardless of the different levels at which the heating element or elements are positioned, it is not necessary to close a manually operable switch for each heating element that is employed and to open a manually operable switch in each circuit in which a heating element is'not employed. It is only necessary, in accord with this invention, to place in operative positions" at different levels those heating elements that are required to develop a particular heating pattern and in so 'doing close certain switches in the control circuit; and to employ structural members in place of heating elements at those levels at which heating elements are not required in order to close other switches in the control circuit, whereby the control circuit will be closed and completed and then render the heating circuit operable to connect to a source of electrical energy the heating elements which are in operative positions.

Iclaim:

1. In an oven of the class described having, in combination:

a. a plurality of walls defining a space for treating food therein, said walls including a rear wall;

b. a plurality of electric heating elements insertable into operative positions in said space and removable therefrom;

c. a control circuit comprising a plurality of switches connected in series, each of said switches having a pair of cooperating first stationary contacts and a movable coneach structure, when said contactor thereon is moved to a switch closing position in said space, also functioning to move said heating element thereon into an operative position in said space;

'. switch means in said heating circuit for connecting and disconnecting said heating elements to and from a source of electrical energy when said heating elements are in operative positions in said space, said switch means normally functioning to disconnect said heating elements from the source of electrical energy; and

. said contactors are similar with each one of said contacmeans responsive to closing of all of said switches in said control circuit by said contactors for rendering said switch means operable to connect said heating elements in said heating circuit to the source of electrical energy. An oven as set forth in claim 1 in which:

. said pairs of first and second contacts on said connecting members are similar;

tors being capable of bridging any one of said pairs of first contacts on said different connecting members; and

. each of said independently movable structures having a contactor and heating element as unitary parts thereof being capable of bridging any one of said pairs of second contacts on said different connecting members.

3. In an oven of the class described having, in combination:

a plurality of walls defining a space for treating food therein, said walls including a rear wall;

an electric heating element insertable into different operative positions in said space and removable therefrom;

. a control circuit comprising a plurality of switches consaid rear wall of the oven being provided with a plurality of connecting members vertically arranged with respect to one another, each of said connecting members including a pair of said first contacts and a pair of said second contacts;

. each of said movable contactors in its switch closing position being disposed in said space and functioning to bridge one of said pairs of first stationary contacts;

one of said contactors comprising a movable structure having as a unitary part thereof said electric heating element which is electrically insulated from said contactor;

said structure, when said contactor thereon is moved to a switch closing position at different connecting members in said space, also functioning to move said heating element thereon into different operative positions in said space;

. switch means in said heating circuit for connecting and disconnecting said heating element to and from a source of electrical energy when said heating element is in an operative position in said space, said switch means normally functioning .to disconnect said heating element from the source of electrical energy; and

. means responsive to closing of all of said switches in said control circuit by said contactors for rendering said switch means operable to connect said heating element in said heating circuit to the source of electrical energy.

4. An oven as set forth in claim 3 in which: a. said pairs of first and second contacts on said connecting members are similar;

b. said contactors are similar with each one of said contactors being capable of bridging any one of said pairs of first contacts on said different connecting members; and

c. said movable structure having said one contactor and said heating element as unitary parts thereof being capable of bridging any one of said pairs of second contacts on said different connecting members.

5. In an oven of the class described having, in combination:

c. a control circuit comprising a plurality of switches connected in series, each of said switches having a pair of cooperating first stationary contacts and a movable contactor for closing said first contacts;

d. a heating circuit comprising a plurality of pairs of cooperating second stationary contacts, each of said pairs of second contacts being bridged and closed by one of said heating elements when it is inserted into an operative position in said space;

e. said rear wall of the oven being provided with a plurality of connecting members vertically arranged with respect to one another, each of said connecting members including a pair of said first contacts and a pair of said second contacts;

each of said movable contactors in its switch closing position being disposed in said space and functioning to bridge one of said pairs of first stationary contacts;

g. a plurality of said contactors each comprising a movable structure having as a unitary part thereof one of said electric heating elements which is electrically insulated from said contactor thereon;

. each structure, when said contactor thereon is moved to a switch closing position in said space, also functioning to move said heating element thereon into an operative position in said space,

. switch means in said heating circuit for. connecting and disconnecting said heating elements to and from a source of electrical energy when said heating elements are in operative positions in said space, said switch means normally functioning to disconnect said heating elements from the source of electrical energy; and

j. means responsive to closing of all of said switches in said control circuit by said contactors for rendering said switch means operable to connect said heating elements in said heating circuit to the source of electrical energy.

. An oven as set forth in claim 5 in which:

. said contactors are similar with each one of said contactors being capable of bridging any one of said pairs of first contacts on said different connecting members; and

. each of said movable structures having a contactor and heating element as unitary parts thereof being capable of bridging any one of said pairs of second contacts on said different connecting members.

7. An oven as set forth in claim 3 in which said structure, when said contactor thereon is moved to a switch closing position in said space and closes a pair of cooperating first contacts associated with one of said. connecting members, said heating element thereon is moved into an operative position in said space and closes a pair of cooperating second contacts also associated with said one connecting member.

8. An oven as set forth in claim 3 in which said pairs of cooperating first and second contacts are horizontally disposed in a group on said connecting members, said pair of t second contacts being at opposing ends of the group and said pair of first contacts being between said pair of second contacts.

9. An oven as set forth in claim 3 in which said structure comprises a body of insulating material, said contactor forming a part of said structure comprising a pair of spaced first plugs carried by said body and electrically connected to one another, said pairs of first contacts on said connecting members comprising spaced socket outlets arranged to receive said pair of first plugs to bridge and close said first contacts, a pair of spaced second plugs carried by said body and to which the opposing ends of said heating element are connected, and said pairs of second contacts on said connecting members comprising spaced socket outlets arranged toreceive said pair of second plugs to maintain said heating element in an operative position in said space.

10. An oven as set forth in claim 3 in which each contactor includes a body of insulating material, each of a said contactors comprising a pair of spaced plugs carried by an insulating body and electrically connected to one another, and said pairs of first contacts on said connecting members comprising spaced socket outlets arranged to receive said plugs to bridge and close said first contacts.

11. An oven as set forth in claim which includes a U- shaped frame having opposing sides and a closed end, means for supporting the opposing sides of said frame in said space for sliding movement therein toward and from the rear wall thereof with the closed end of said frame movable into close proximity to the rear wall, and means for mounting said body of insulating material of one of said contactors on the closed end of said frame.

. 12. An oven as set forth in claim 11 which includes handles fixed to the forward ends of the opposing sides of said frame.

13. An oven as set forth in claim 10 which includes an open cup-shaped vessel defining a first hood or shroud, and means for mounting said body of insulating material for one of said contactors insaid vessel at the bottom thereof with said plugs extending toward the open end of said vessel.

14. An oven as set forth in claim 13 in which one of said connecting members includes an opencup-shaped vessel defining a second hood or shroud projecting forward from the rear wall of said space, and said first and second hoods or shrouds being in telescopic relation when said socket outlets of said one connecting member receive a pair of said plugs to bridge and close said socket outlets serving as said first contacts.

15. An oven as set forth in claim 9 which includes an open cup-shaped vessel defining a first hood or shroud, and means for mounting said body of insulating material in said vessel at the bottom thereof with said first and second plugs extending toward the open end of said vessel.

16. An oven as set forth in claim 15 in which one of said connecting members includes an open cup-shaped vessel defining a second hood or shroud projecting forward from the rear wall of said space, and said first and second hoods or shrouds being in telescopic relation when said socket outlets of said one connecting member receive a pair of said first plugs to bridge and close said first contacts and receive a pair of said second plugs to maintain said heating element in an operative position in said heating space.

17. An oven as set forth in claim 9 in which said electrical heating element is provided with an outer insulating sheath, a frame, means for carrying said heating element on said frame, means for supporting the opposing sides'of said frame in said space for sliding movement therein toward and from the rear wall thereof, means for carrying said body of insulating material on said frame, a third plug which is carried by said body, means conductively connecting said third plug to said frame and to the insulating sheath of said-heating element, said connecting members including third contacts comprising socket outlets arranged to receive said'third plug, and means for grounding said last-mentioned socket outlets serving as said third contacts, said third contacts on said connecting members being arranged to receive said third plug before said pairs of first contacts receive said first pair of plugs and before said second pairs of contacts receive said second pair of plugs.

18. An oven as set forth in claim 17 in which said means conductively connecting said third plug to said frame and to said insulating sheath ofsaid heating element includes an open cup-shaped vessel defining a hood or shroud for housing said body of insulating material with said pairs of first and second plugs and said third plug extending toward the open end of said vessel.

19. An oven as set forth in claim 11 which includes a third plug carried by said body of insulating material of said one contactor, means conductively connecting said third plug to said frame, said connecting members including third contacts comprising socket outlets arranged to receive said third plug, and means for grounding said last-mentioned socket outlets serving as said third contacts, said third contacts on said connecting members being arranged to receive said third plug before said pairs of first contacts receive said first-pair of plugs.

20. An oven as set forth in claim 19 in which said means conductively connecting said third plug to said frame includes an open cup-shaped vessel defining a hood or shroud for housing said body of insulating material of said one contactor with said pair of first plugs and said third plug extending toward the open end of said vessel.

21. An oven as set forth in claim 10 which includes a third plug carried by each of said bodies of insulating material, each of said contactors including a part serving as a hand grip, means conductively connecting said third plugs to said lastmentioned parts, said connecting members including third contacts comprising socket outlets arranged to receive said third plugs, and means for grounding said last-mentioned socket outlets serving as said third contacts, said third con-